If this solution does not fix the issue, please refer to the Cite While You Write FAQs page from the EndNote website (linked below) - scroll down to find the answer that fits your versions of Word and EndNote. To re-instate EndNote X8/X9 in Word on Macs, please see the first link below.
A Microsoft account is an e-mail address and password that you use to sign in to Windows and other Microsoft. Make sure the box beside it is ticked, then click OK.
If CWYW is installed, then EndNote Cite While You Write will appear as one of the add-ins available.If it is not listed, then go down to the bottom of the window to the Manage drop-down list.Under the heading Active Application Add-ins, check whether you have the EndNote Cite While You Write COM Add-in (see the Type column).Select Add-Ins from the left hand menu.In Word, click the File tab and choose Options.To reinstate the EndNote tab in Word on Windows devices, please follow the instructions below in the first instance: Premium features such as SharePoint support, version history and Outlook integration were. Below are solutions for both Mac and Windows devices: OneNote for Windows and Mac are both based on a freemium model. There may be a number of reasons why, if you have had the Cite While You Write (CWYW) add-in showing in Word previously, it may have dropped off.